Emergency lighting on contractor switched lighting circuits

NigelMarsh · Jun 8, 2014

I have been asked to get the emergency lighting working at a nursery. They had a switch put in at the entrance to the building that switches off all of the lights in the building when they lock up at the end of the day. All lighting circuits are hanging off a contactor connected to this switch, so they are cutting power to the light circuit MCBs and pretty much simulating failed circuits when using this, "master" switch.

whoever fitted this switch saw this and wired all of their emergency lighting into its own circuit to prevent it kicking in when the lights are switched off in the evening.

this obviously makes the emergency lighting pretty much useless for its main function.

they don't want to get rid of the master switch, but the want the emergency lighting to kick in when it's local lighting circuit fails. Doh!

Any ideas on how this can be achieved without losing the master switch, even if it means switching all lighting off using a different method? I'm going grey trying to come up with a simple solution.

:banghead:

Knobhead · Jun 9, 2014

It was something stuck in the murky recesses of my mind.

tazz · Jun 9, 2014

Tony said:
It was something stuck in the murky recesses of my mind.

its called motor phase failure, and with dealing with switchgear....can understand the logic

eNigMar · Jun 9, 2014

Wow! This has taken off.

I'm the Op, but I was informed this moring that I had two accounts and one had to go. I forgot about this second one, so let the one that I posted this thread as go. Hence me replying with this account.

It's single phase in a large converted house with two floors and a loft space. There are three downstairs lighting circuits, two upstairs and one for the loft. I don't do much in the way of emergency lighting and have only attended a days course on it out of interest, I was originally there to replace some broken outside lights, a few cracked sockets and a fluorescent batten in the staff room, but was asked about this.

The emergencies are non-maintained and I believe from what I've been told, were originally wired to the closest fitting, but when the contacter was put in for the master switch, they were all put on to their own single circuit (10x ELs).

I was thinking that if just one lighting circuit circuit died, if the emergencies were wired to the contacter feed, they wouldn't come on because they'd still have power. It would take the feed circuit to die before they came on.

Maybe updating to maintained lights would be the way to go.

Sorry about the late reply, it was my anniversary yesterday and I had to go do some anniversary stuff after posting.

D Skelton · Jun 10, 2014

Hey, this situation is exactly what this set up is designed for:

[ElectriciansForums.net] Emergency lighting on contractor switched lighting circuits

Key switch at the front door turns off all lights but leaving the emergency function intact.

Out of each lighting MCB (four of them) comes a feed which is then split across two seperate poles of the four DP contactors that you can see in this picture. The first two contactors (four poles in total) make up the permanent lives of the four emergency lighting circuits, the second two make up the switched live for each of the four emergency lighting circuits. The second two contactor's coils are controlled by the key switch, thus leaving the permanent live energised at all times, each permanent live and switched live fed from the same MCB remember. The first two contactor's coils are fed directly from the MCB for the control circuit/key switch meaning if the control circuit fails, the emergency lighting operates. The installation is essentially fail safe.

Apologies for the crap drawing, but below is a simplified version (one circuit) of what the picture above is doing:

Knobhead · Jun 10, 2014

eNigMar said:
Wow! This has taken off. I'm the Op, but I was informed this moring that I had two accounts and one had to go. I forgot about this second one, so let the one that I posted this thread as go. Hence me replying with this account.

Ask the moderators nicely to combine your other account with this one. You retain your post count that way.

Guest77 · Jun 10, 2014

eNigMar said:
Wow! This has taken off. I'm the Op, but I was informed this moring that I had two accounts and one had to go. I forgot about this second one, so let the one that I posted this thread as go. Hence me replying with this account.

It's single phase in a large converted house with two floors and a loft space. There are three downstairs lighting circuits, two upstairs and one for the loft. I don't do much in the way of emergency lighting and have only attended a days course on it out of interest, I was originally there to replace some broken outside lights, a few cracked sockets and a fluorescent batten in the staff room, but was asked about this.

The emergencies are non-maintained and I believe from what I've been told, were originally wired to the closest fitting, but when the contacter was put in for the master switch, they were all put on to their own single circuit (10x ELs).

I was thinking that if just one lighting circuit circuit died, if the emergencies were wired to the contacter feed, they wouldn't come on because they'd still have power. It would take the feed circuit to die before they came on.

Maybe updating to maintained lights would be the way to go.

Sorry about the late reply, it was my anniversary yesterday and I had to go do some anniversary stuff after posting.

Yes for something so simple even I am suprised it has :smilielol5: